daltk / diff-lcs

Generate difference sets between Ruby sequences.

Diff::LCS¶ ↑

home

diff-lcs.rubyforge.org/

code

github.com/halostatue/diff-lcs

bugs

github.com/halostatue/diff-lcs/issues

rdoc

rubydoc.info/github/halostatue/diff-lcs

Description¶ ↑

Diff::LCS computes the difference between two Enumerable sequences using the McIlroy-Hunt longest common subsequence (LCS) algorithm. It includes utilities to create a simple HTML diff output format and a standard diff-like tool.

This is release 1.2. Everyone is strongly encouraged to upgrade to this version as it fixes all known outstanding issues.

Synopsis¶ ↑

Using this module is quite simple. By default, Diff::LCS does not extend objects with the Diff::LCS interface, but will be called as if it were a function:

require 'diff/lcs'

seq1 = %w(a b c e h j l m n p)
seq2 = %w(b c d e f j k l m r s t)

lcs = Diff::LCS.LCS(seq1, seq2)
diffs = Diff::LCS.diff(seq1, seq2)
sdiff = Diff::LCS.sdiff(seq1, seq2)
seq = Diff::LCS.traverse_sequences(seq1, seq2, callback_obj)
bal = Diff::LCS.traverse_balanced(seq1, seq2, callback_obj)
seq2 == Diff::LCS.patch!(seq1, diffs)
seq1 == Diff::LCS.unpatch!(seq2, diffs)
seq2 == Diff::LCS.patch!(seq1, sdiff)
seq1 == Diff::LCS.unpatch!(seq2, sdiff)

Objects can be extended with Diff::LCS:

seq1.extend(Diff::LCS)
lcs = seq1.lcs(seq2)
diffs = seq1.diff(seq2)
sdiff = seq1.sdiff(seq2)
seq = seq1.traverse_sequences(seq2, callback_obj)
bal = seq1.traverse_balanced(seq2, callback_obj)
seq2 == seq1.patch!(diffs)
seq1 == seq2.unpatch!(diffs)
seq2 == seq1.patch!(sdiff)
seq1 == seq2.unpatch!(sdiff)

By requiring ‘diff/lcs/array’ or ‘diff/lcs/string’, Array or String will be extended for use this way.

Note that Diff::LCS requires a sequenced enumerable container, which means that the order of enumeration is both predictable and consistent for the same set of data. While it is theoretically possible to generate a diff for an unordered hash, it will only be meaningful if the enumeration of the hashes is consistent. In general, this will mean that containers that behave like String or Array will perform best.

History¶ ↑

Diff::LCS is a port of Perl’s Algorithm::Diff that uses the McIlroy-Hunt longest common subsequence (LCS) algorithm to compute intelligent differences between two sequenced enumerable containers. The implementation is based on Mario I. Wolczko’s Smalltalk version 1.2 (1993) and Ned Konz’s Perl version Algorithm::Diff 1.15.

This library is called Diff::LCS because of an early version of Algorithm::Diff which was restrictively licensed.

Continuous Integration Status¶ ↑

<img src=“https://travis-ci.org/halostatue/diff-lcs.png” />

Contributing¶ ↑

If you’d like to hack on Diff::LCS, start by forking the repo on GitHub:

github.com/halostatue/diff-lcs

The best way to get your changes merged back into core is as follows:

1. Clone down your fork.

2. Create a thoughtfully named topic branch to contain your change.

3. Hack away.

4. Add tests and make sure everything still passes by running rake.

5. If you are adding new functionality, document it in the README.

6. Do not change the version number, we will do that on our end.

7. If necessary, rebase your commits into logical chunks, without errors.

8. Push the branch up to GitHub.

9. Send a pull request for your branch

:include: Contributing.rdoc

:include: License.rdoc